Add option for slow motion to be slow-audio instead of extended audio#2078

When doing slow-motion edits, audio will extend, which is basically to copy itself and fill in for the extra footage of the same clip. Sometimes this doesn’t sound good.

So please add an option for the audio to either extend or actually sound slow with the clip as well. And would it be possible to add a transition effect to the slow-mo, so it doesn’t instantly become slow, but sort of slows down?